Vega FEM Library (v1.1) User's Manual - University of Southern ...

virtual int SetState(double * q, double * qvel=NULL)
Sets the position (and optionally the velocity) buffer based on the parameters, and calculates the appropriate
acceleration buffer values using implicit Euler, assuming no external forces. Returns 0 if successful, 1
otherwise.
virtual int DoTimestep()
Runs a timestep of implicit Euler, and updates the internal position, velocity, and acceleration buffers
accordingly. Returns 0 if successful, 1 otherwise.
class CentralDifferencesSparse : public IntegratorBaseSparse Implements the explicit central differences
integrator.
CentralDifferencesSparse(int numDOFs, double timestep,
SparseMatrix * massMatrix,
ForceModel * forceModel,
int numConstrainedDOFs=0, int * constrainedDOFs=NULL,
double dampingMassCoef=0.0, double dampingStiffnessCoef=0.0,
int tangentialDampingMode=1, int numSolverThreads=0)
Initializes the integrator settings via the IntegratorBaseSparse constructor, and selects the number of
threads to use for the sparse linear solver. Tangential damping mode controls how often the Rayleigh damping
matrix is recomputed. This damping matrix depends on the tangent stiffness matrix, which changes in time.
When 0, the damping matrix is never updated. The system matrix is then constant, so one can factor it
only once. However, this is not recommended for large deformations as it leads to damping artifacts. When
tangentialDampingMode > 0, the damping matrix is updated every “tangentialDampingMode”th timestep.
Default is 1, i.e., update at every timestep.
virtual int SetState(double * q, double * qvel=NULL)
Sets the position (and optionally velocity) buffers. Always returns 0.
virtual int DoTimestep()
Runs a timestep of explicit central differences, and updates the internal position, velocity and acceleration
buffers accordingly. Returns 0 if successful, 1 otherwise.
class EulerSparse : public IntegratorBaseSparse Implements explicit Euler integration, with a flag
to enable symplectic Euler integration. Because this class never forms the tangent stiffness matrix, damping
is controlled via mass-based damping only.
EulerSparse(int r, double timestep, SparseMatrix * massMatrix,
ForceModel * forceModel,
int symplectic=0, int numConstrainedDOFs=0,
int * constrainedDOFs=NULL, double dampingMassCoef=0.0)
Initializes the integrator settings via the IntegratorBaseSparse constructor, and sets whether to perform
symplectic integration.
virtual int SetState(double * q, double * qvel=NULL)
Sets the position (and optionally velocity) buffers based on the parameters, and sets the acceleration
buffer via explicit (or symplectic) Euler assuming no external forces. Returns 0 if successful, 1 otherwise.
virtual int DoTimestep()
Runs a timestep of explicit (or symplectic) Euler, and updates the internal position, velocity, and acceleration
buffers accordingly. Returns 0 if successful, 1 otherwise.
15